Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in the gram-staining method of bacterial differentiation. They are characterized by their cell envelopes, which are composed of a thin peptidoglycan cell wall sandwiched between an inner cytoplasmic cell membrane and a bacterial outer membrane.
Neisseria gonorrhoeae, also known as gonococcus (singular), or gonococci (plural) is a species of Gram-negative diplococci bacteria isolated by Albert Neisser in 1879. It causes the sexually transmitted genitourinary infection gonorrhea as well as other forms of gonococcal disease including disseminated gonococcemia, septic arthritis, and gonococcal ophthalmia neonatorum.
Neisseria is a large genus of bacteria that colonize the mucosal surfaces of many animals. Of the 11 species that colonize humans, only two are pathogens, N. meningitidis and N. gonorrhoeae. Most gonococcal infections are asymptomatic and self-resolving, and epidemic strains of the meningococcus may be carried in >95% of a population where systemic disease occurs at <1% prevalence.
The bacterial capsule is a large structure common to many bacteria. It is a polysaccharide layer that lies outside the cell envelope, and is thus deemed part of the outer envelope of a bacterial cell. It is a well-organized layer, not easily washed off, and it can be the cause of various diseases.
Neisseria meningitidis, often referred to as meningococcus, is a Gram-negative bacterium that can cause meningitis and other forms of meningococcal disease such as meningococcemia, a life-threatening sepsis. The bacterium is referred to as a coccus because it is round, and more specifically, a diplococcus because of its tendency to form pairs. About 10% of adults are carriers of the bacteria in their nasopharynx. As an exclusively human pathogen it is the main cause of bacterial meningitis in children and young adults, causing developmental impairment and death in about 10% of cases. It causes the only form of bacterial meningitis known to occur epidemically, mainly in Africa and Asia. It occurs worldwide in both epidemic and endemic form. N. meningitidis is spread through saliva and respiratory secretions during coughing, sneezing, kissing, chewing on toys and even through sharing a source of fresh water. It has also been reported to be transmitted through oral sex and cause urethritis in men. It infects its host cells by sticking to them with long thin extensions called pili and the surface-exposed proteins Opa and Opc and has several virulence factors.
Staphylococcus haemolyticus is a member of the coagulase-negative staphylococci (CoNS). It is part of the skin flora of humans, and its largest populations are usually found at the axillae, perineum, and inguinal areas. S. haemolyticus also colonizes primates and domestic animals. It is a well-known opportunistic pathogen, and is the second-most frequently isolated CoNS. Infections can be localized or systemic, and are often associated with the insertion of medical devices. The highly antibiotic-resistant phenotype and ability to form biofilms make S. haemolyticus a difficult pathogen to treat. Its most closely-related species if Staphylococcus borealis.
A diplococcus is a round bacterium that typically occurs in the form of two joined cells.
Levilactobacillus brevis(previously Lactobacillus brevis) is a gram-positive, rod shaped species of lactic acid bacteria which is heterofermentative, creating CO2, lactic acid and acetic acid or ethanol during fermentation. L. brevis is the type species of the genus Levilactobacillus (previously L. brevis group), which comprises 24 species (http://www.lactobacillus.ualberta.ca/, http://www.lactobacillus.uantwerpen.be/). It can be found in many different environments, such as fermented foods, and as normal microbiota. L.brevis is found in food such as sauerkraut and pickles. It is also one of the most common causes of beer spoilage. Ingestion has been shown to improve human immune function, and it has been patented several times. Normal gut microbiotaL.brevis is found in human intestines, vagina and feces.
Pasteurella multocida is a Gram-negative, nonmotile, penicillin-sensitive coccobacillus of the family Pasteurellaceae. Strains of the species are currently classified into five serogroups based on capsular composition and 16 somatic serovars (1–16). P. multocida is the cause of a range of diseases in mammals and birds, including fowl cholera in poultry, atrophic rhinitis in pigs, and bovine hemorrhagic septicemia in cattle and buffalo. It can also cause a zoonotic infection in humans, which typically is a result of bites or scratches from domestic pets. Many mammals and birds harbor it as part of their normal respiratory microbiota.
Neisseria lactamica is a gram-negative diplococcus bacterium. It is strictly a commensal species of the nasopharynx. Uniquely among the Neisseria they are able to produce β-D-galactosidase and ferment lactose.
The Human Microbiome Project (HMP) was a United States National Institutes of Health (NIH) research initiative to improve understanding of the microbial flora involved in human health and disease. Launched in 2007, the first phase (HMP1) focused on identifying and characterizing human microbial flora. The second phase, known as the Integrative Human Microbiome Project (iHMP) launched in 2014 with the aim of generating resources to characterize the microbiome and elucidating the roles of microbes in health and disease states. The program received $170 million in funding by the NIH Common Fund from 2007 to 2016.
Gonorrhea, colloquially known as the clap, is a sexually transmitted infection (STI) caused by the bacterium Neisseria gonorrhoeae. Infection may involve the genitals, mouth, and/or rectum. Infected men may experience pain or burning with urination, discharge from the penis, or testicular pain. Infected women may experience burning with urination, vaginal discharge, vaginal bleeding between periods, or pelvic pain. Complications in women include pelvic inflammatory disease and in men include inflammation of the epididymis. Many of those infected, however, have no symptoms. If untreated, gonorrhea can spread to joints or heart valves.
Cystine tryptic agar (CTA), also known as cystine trypticase agar, is a growth medium used for the identification of microorganisms.
Neisseria mucosa is a species of Neisseria.
Hafnia is a genus of Gram-negative, facultatively anaerobic, rod-shaped bacteria in the family Hafniaceae.
Neisseria gonorrhoeae, the bacterium that causes the sexually transmitted infection gonorrhea, has developed antibiotic resistance to many antibiotics. The bacteria was first identified in 1879.
Neisseria bacilliformis is a bacterium commonly found living as a commensal in the mucous membranes of mammals. However, depending on host immunocompetence, there have been documented cases of N. bacilliformis infections of the respiratory tract and oral cavity thus making it an opportunistic pathogen. It was originally isolated from patients being treated in a cancer center. Rarely, a more serious infection such as endocarditis can occur often as a result of a predisposing condition.
Neisseria cinerea is a commensal species grouped with the Gram-negative, oxidase-positive, and catalase-positive diplococci. It was first classified as Micrococcus cinereus by Alexander von Lingelsheim in 1906. Using DNA hybridization, N. cinerea exhibits 50% similarity to Neisseria gonorrhoeae.
In 1928, Neisseria flavescens was first isolated from cerebrospinal fluid in the midst of an epidemic meningitis outbreak in Chicago. These gram-negative, aerobic bacteria reside in the mucosal membranes of the upper respiratory tract, functioning as commensals. However, this species can also play a pathogenic role in immunocompromised and diabetic individuals. In rare cases, it has been linked to meningitis, pneumonia, empyema, endocarditis, and sepsis.
Diagnostic microbiology is the study of microbial identification. Since the discovery of the germ theory of disease, scientists have been finding ways to harvest specific organisms. Using methods such as differential media or genome sequencing, physicians and scientists can observe novel functions in organisms for more effective and accurate diagnosis of organisms. Methods used in diagnostic microbiology are often used to take advantage of a particular difference in organisms and attain information about what species it can be identified as, which is often through a reference of previous studies. New studies provide information that others can reference so that scientists can attain a basic understanding of the organism they are examining.
